Ukrainian soldiers sit on an armoured personnel carier at a Ukrainian checkpoint near the eastern town of Slaviansk
Ukrainian soldiers sit on an armoured personnel carrier at a Ukrainian checkpoint near the eastern town of Slaviansk May 2, 2014. Ukrainian forces attacked the rebel-held city of Slaviansk before dawn on Friday and pro-Russia separatists shot down at least one attack helicopter, killing a pilot, in a sharp escalation of the conflict. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST MILITARY)
Civilians talk with Ukrainian troops at a checkpoint near the town of Slaviansk
Civilians talk with Ukrainian troops at a checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. Ukrainian forces attacked the rebel-held city of Slaviansk before dawn on Friday and pro-Russia separatists shot down at least one attack helicopter, killing a pilot, in a sharp escalation of the conflict. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST MILITARY)
Ukraine says two killed when helicopters shot down in Slaviansk
UKRAINE-CRISIS/DEFENCE (URGENT):Ukraine says two killed when helicopters shot down in Slaviansk
Kremlin says Kiev destroys hope for Geneva accord - report
UKRAINE-CRISIS/KREMLIN (URGENT):Kremlin says Kiev destroys hope for Geneva accord - report
A Ukrainian soldier looks on at a Ukrainian checkpoint near the eastern town of Slaviansk
A Ukrainian soldier looks on at a Ukrainian checkpoint near the eastern town of Slaviansk May 2, 2014. Ukrainian forces attacked the rebel-held city of Slaviansk before dawn on Friday and pro-Russia separatists shot down at least one attack helicopter, killing a pilot, in a sharp escalation of the conflict. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST)
Ukrainian troops guard a checkpoint near the town of Slaviansk in eastern Ukraine
Ukrainian troops guard a checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. Ukrainian forces attacked the rebel-held city of Slaviansk before dawn on Friday and pro-Russia separatists shot down at least one attack helicopter, killing a pilot, in a sharp escalation of the conflict. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST MILITARY)
A Ukrainian soldier stands guard on the railway tracks near the town of Slaviansk
A Ukrainian soldier stands guard on the railway tracks near the town of Slaviansk in eastern Ukraine May 2, 2014. Ukrainian forces attacked the rebel-held city of Slaviansk before dawn on Friday and pro-Russia separatists shot down at least one attack helicopter, killing a pilot, in a sharp escalation of the conflict. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST MILITARY)
A woman stands with Ukrainian troops at a checkpoint near the town of Slaviansk
A woman stands with Ukrainian troops at a checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. Ukrainian forces attacked the rebel-held city of Slaviansk before dawn on Friday and pro-Russia separatists shot down at least one attack helicopter, killing a pilot, in a sharp escalation of the conflict. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST MILITARY)
A Ukrainian military helicopter lands near a Ukrainian checkpoint near the town of Slaviansk
A Ukrainian military helicopter lands near a Ukrainian checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. Ukrainian forces attacked the rebel-held city of Slaviansk before dawn on Friday and pro-Russia separatists shot down at least one attack helicopter, killing a pilot, in a sharp escalation of the conflict. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST MILITARY)
A Ukrainian military helicopter lands near a Ukrainian checkpoint near the town of Slaviansk
A Ukrainian military helicopter lands near a Ukrainian checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. Ukrainian forces attacked the rebel-held city of Slaviansk before dawn on Friday and pro-Russia separatists shot down at least one attack helicopter, killing a pilot, in a sharp escalation of the conflict. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST MILITARY)